In the distribution of electrical welding rods or welding electrodes, it is common to package the rods in cardboard cartons, usually with several pounds of rods in each carton. Since the cartons are not air-tight or moisture proof, it is desirable to use the welding rods in a relatively short time, especially if an open box of electrodes is exposed to an environment having a high humidity or moisture content.
It is highly desirable for the hydrophilic flux coating on welding electrodes or rods to have a low hydrogen content, especially when the rods are used to produce a weld having X-ray quality or where the base metal has a tendency to crack or has an alloy content greater than mild steel. A low hydrogen content is also desirable when the materials to be welded are relatively thick. Hydrogen is soluble in molten metal and is really absorbed in the weld during the welding operation. If moisture enters the welding operation, the moisture is disassociated to produce free hydrogen.
Hydrogen in the weld metal may cause porosity or embrittlement or cracking, and a small amount of moisture may cause an erratic arc, increased splatter and internal porosity which is difficult to detect. When hydrogen is held in the crystalline structure of steel, the steel may have embrittlement which may be observed as low ductility during a tensile test or low impact values or early failure in a bend test. The greatest problem with cracking caused by hydrogen arises in the heat-affected zones of hardenable steels. The hydrogen diffuses into the heated zone adjacent the weld metal and causes stress cracks. Thus it has been found desirable to maintain the moisture content of low hydrogen electrode coatings below 0.3%.